Heart and Blood 103 



every motion of an animal primarily endowed with 

 a motive spirit (as Aristotle has it, 1 ) is contractile ; and 

 in what way the word vcupov is derived from vev'w, nuto, 

 contraho ; and how Aristotle was acquainted with the 

 muscles, and did not unadvisedly refer all motion in 

 animals to the nerves, or to the contractile element, 

 and therefore called those little bands in the heart 

 nerves all this, if I am permitted to proceed in my 

 purpose of making a particular demonstration of the 

 organs of motion in animals from observations in my 

 possession, I trust I shall be able to make sufficiently 

 plain. 



But that we may go on with the subject we have in 

 hand, viz. the use of the auricles in filling the ventricles : 

 we should expect that the more dense and compact the 

 heart, the thicker its parietes, the stronger and more 

 muscular must be the auricle to force and fill it, and 

 vice versa. Now this is actually so : in some the auricle 

 presents itself as a sanguinolent vesicle, as a thin mem- 

 brane containing blood, as in fishes, in which the sac 

 that stands in lieu of the auricle, is of such delicacy 

 and ample capacity, that it seems to be suspended or 

 to float above the heart ; in those fishes in which the 

 sac is somewhat more fleshy, as in the carp, barbel, 

 tench, and others, it bears a wonderful and strong 

 resemblance to the lungs. 



In some men of sturdier frame and stouter make, 

 the right auricle is so strong, and so curiously con- 

 structed within of bands and variously interlacing fibres, 

 that it seems to equal the ventricle of the heart in 

 other subjects; and I must say that I am astonished to 

 find such diversity in this particular in different in- 

 dividuals. It is to be observed, however, that in the 

 foetus the auricles are out of all proportion large, which 

 is because they are present before the heart [the 

 ventricular portion] makes its appearance or suffices for 

 its office even when it has appeared, and they therefore 



1 In the book, de Spiritu, and elsewhere. 



